Solve error high with good track?
Successful reconstruction can only be achieved with accurate tracking

Your error average should be under 1.0 pixels, preferably 0.3.



Issues with your file: Your tracking is not good...

Your trackers are too large, and have few distinct features. Don't track the center of a featureless object, try to track the edges that have contrast.
(read this post on camera tracking markers)

Select any of them and scroll throug the timeline to watch what the tracker is doing:



The shape you are tracking shouldn't be dancing like that. 

It should be more like this:



Go through your trackers ONE BY ONE to fix them.

Instead of using only loc, try loc scale and change from keyframe to Previous frame.



Use the graphs and the dopesheet for the movie clip editor to determine which tracker have a high tracking error and get rid of them and re-track.

READ THIS POST to troubleshoot issues with motion tracking